Virtual Reality-Induced Modification of Vestibulo-Ocular Reflex Gain in Posturography Tests.

Background: The aim of the study was to demonstrate the influence of virtual reality (VR) exposure on postural stability and determine the mechanism of this influence. Methods: Twenty-six male participants aged 21-23 years were included, who underwent postural stability assessment twice before and after a few minute of single VR exposure. The VR projection was a computer-generated simulation of the surrounding scenery. Postural stability was assessed using the Sensory Organization Test (SOT), using Computerized Dynamic Posturography (CDP). Results: The findings indicated that VR exposure affects the visual and vestibular systems. Significant differences (p < 0.05) in results before and after VR exposure were observed in tests on an unstable surface. It was confirmed that VR exposure has a positive influence on postural stability, attributed to an increase in the sensory weight of the vestibular system. Partial evidence suggested that the reduction in vestibulo-ocular reflex (VOR) reinforcement may result in an adaptive shift to the optokinetic reflex (OKR). Conclusions: By modifying the process of environmental perception through artificial sensory simulation, the influence of VR on postural stability has been demonstrated. The validity of this type of research is determined by the effectiveness of VR techniques in the field of vestibular rehabilitation.

Investigations Concerning the Influence of Sleep Disorders on Postural Stability in Young Men.

Lack of sleep is a factor that disrupts the receptors' reception of information from the environment and contributes to the emergence of problems with maintaining balance. The main aim of the study was to determine whether sleep disorders affect postural stability in young men. The study participants were 76 male students who were divided into groups with good and poor sleep quality. The division was made based on the results obtained from the questionnaire of the Pittsburgh Sleep Quality Index (PSQI). In each group, postural stability had been tested using three main tests: Sensory Organization Test (SOT); Motor Control Test (MCT); and Adaptation Test (ADT). The results of the analysis show that the obtained results differ in the examined groups under the SOT test. Different values of the tested parameters were noted among people with poor sleep quality and compared with the values of those who sleep well, which translates into a difference in the ability to maintain balance. The greatest impact is observed when using visual and a vestibular system to maintain a stable posture. It was confirmed that the lack of sleep significantly disturbs postural stability.

The human balance system and gender.

The human body balance system is a complex system of organs and mechanisms, which generate postural reactions to counter the displacement from the equilibrium position of the body centre of gravity, and which control eye movement in order to maintain a stable image of the environment. Computerised Dynamic Posturography (CDP) allows for a quantitative and objective assessment of the sen- sory and motor components of the body balance control system as well as of the integration and adaptive mechanisms in the central nervous system. The aim of this study was to determine the differences, when maintaining body balance, based on the gender of young, healthy people using CDP. The study was carried out on a group of 43 healthy subjects by comparing the effectiveness of the balance system in 22 women and 21 men aged between 20 and 26 years, between 171 and 177 cm in height, and without any clinical symptoms of balance disorders. The men and women were selected such that they did not differ significantly in height and BMI. Using the Equitest posturograph manufactured by NeuroCom International Inc. the following tests were performed: Sensory Organisation Test (SOT), Motor Control Test (MCT) and the Adaptation Test (ADT). The gender of young healthy individuals without any clinical symptoms of balance disorders also does not affect the effectiveness of the sensory system and the use of this signal in maintaining body balance.

[Acoustic analysis of tracheoesophageal speech in comparison to esophageal speech after total laryngectomy]. / Analiza akustyczna mowy przetokowej w porównaniu z mowa przelykowa u chorych po calkowitym usunieciu krtani.

In order to evaluate the vocal quality of tracheo-oesophageal (TE) and oesophageal (E) speech, several acoustic parameters were measured in the acoustic waveform (fundamental frequency, maximum phonation time, maximum intensity) and in the frequency spectrum: harmonicity-to-noise ratio [HNR], pitch perturbation [Jitter], Shimmer. Thirteen patients using tracheo-oesophageal speech (Provox 2 valve) and 11 good oesophageal speakers were evaluated. The control group consisted of 10 healthy men with normal speech. Digital recordings were obtained from examined subjects as they sustained the vowel "a". Maximum phonation time in TE samples was significantly longer than in E speech recordings and similar to the normal speech. The tracheo-oesophageal voices more often showed a detectable fundamental frequency which was fairly stable and lower than in oesophageal and normal speech. In our cohort of patients maximum voice intensity in both groups of alaryngeal speakers was similar and lower than in control group. The Jitter and Shimmer results of TE speech were similar to those of E speech and higher than in controls. HNR was significantly higher in TE speech than in E voice and three times lower in comparison to normal speech. The results of this investigation indicate that TE speech is more like normal speech than is E voice.

The effect of height and BMI on computer dynamic posturography parameters in women.

The human body's posture control is a complex system of organs and mechanisms which controls the body's centre of gravity (COG) over its base of support (BOS). Computerised Dynamic Posturography (CDP) allows for the quantitative and objective assessment of the sensory and motor components of the body's posture control system as well as of the integration and adaptation mechanisms in the central nervous system. The aim of this study was to assess the relationships between the body's height and BMI on CDP results in a group of young healthy women without any clinical symptoms of balance disorders. It was found that the MS depended significantly on the height and BMI of the subjects as well as on the SOT conditions. As the height and BMI increased the MS value decreased. The postural response latency (LC) in the MCT statistically significantly depended only on height and showed a positive correlation. The postural response latency increased with height. The postural response amplitude for both right and left lower limbs significantly depended on height and BMI, but only for the backward movement of the platform. The response amplitude for all platform translations under all MCT conditions increased with height and BMI. The body's resultant imbalance caused by the platform perturbations in the ADT was greater in shorter people and those with a lower BMI.

Recurrent neural networks in computer-based clinical decision support for laryngopathies: an experimental study.

The main goal of this paper is to give the basis for creating a computer-based clinical decision support (CDS) system for laryngopathies. One of approaches which can be used in the proposed CDS is based on the speech signal analysis using recurrent neural networks (RNNs). RNNs can be used for pattern recognition in time series data due to their ability of memorizing some information from the past. The Elman networks (ENs) are a classical representative of RNNs. To improve learning ability of ENs, we may modify and combine them with another kind of RNNs, namely, with the Jordan networks. The modified Elman-Jordan networks (EJNs) manifest a faster and more exact achievement of the target pattern. Validation experiments were carried out on speech signals of patients from the control group and with two kinds of laryngopathies.